The present invention relates to formulations comprising quaternary ammonium compounds substituted by a trialkoxysilane group, hereinafter called siloxane quats for short, and special solvents and also to the preparation and use of these siloxane quat formulations.
There is extensive patent literature relating to the preparation of quaternary ammonium compounds having a trialkoxysilane substituent and one or two fatty alkyl radicals and to the use of these compounds as biocides. The trialkoxysilane substituent augments the tendency of quaternary ammonium compounds to form permanent finishes on surfaces of various kinds, for example textiles composed of polyamide, cotton or polyester, wood, paper, glass, plastics or metals. The surfaces finished with these compounds acquire durable water-resistant antimicrobial protection as a result. For instance, a solution of 3-(trimethoxysilyl)propyloctadecyl-dimethylammonium chloride in methanol is commercially available for the antimicrobial finishing of various surfaces.
EP-A-0 108 853 describes the preparation of 3-(trimethoxysilyl)propyl-didecylmethylammonium chloride from 3-chloropropyltrimethoxysilane and didecylmethylamine without solvent or in a solvent such as methanol. Without further details being provided, solvents useful for bactericidal or fungicidal applications are said to be water, water-miscible solvents such as alcohols, for example methanol, ethanol and butanol, methylcellosolve, ethylcellosolve and ketones such as methyl ethyl ketone. For textile treatment, solvents such as hydrocarbons, chlorinated hydrocarbons, ethers and benzene are said to be alternatively useful.
WO-87/06587 discloses preparing compounds of the type 
by reacting tertiary amines with 3-chloropropyltrialkoxysilanes under alkali metal iodide catalysis. The solvent for this catalytic reaction is selected from certain glycol ethers.
Further quaternary ammonium compounds, including some substituted by trialkoxysilane radicals, are recited in U.S. Pat. No. 4,883,917. They are prepared at 50-100xc2x0 C. either without solvent or in the solvents used in many examples, ethyl acetate, methyl ethyl ketone and para-dioxane. Further possible solvents for quaternization reactions are said to be tetrahydrofuran, dimethoxyethane and diglyme.
EP-A-0 415 540 describes using quaternary ammonium compounds substituted by trialkoxysilane radicals for the antibacterial and fungicidal finishing of textile fabrics to eliminate odor. The preferred compound is 3-(trimethoxysilyl) propyloctadecyl-dimethylammonium chloride. A method for preparing these compounds is not disclosed, although there is a reference to the prior art.
K. J. Hxc3xcttinger, Chemiker-Zeitung, 111 (1987) pages 213-220 describes the use of quaternary trialkoxysilane for preparing carrier-bound agents for disinfecting water. With this technique, unlike chlorination or ozonization, say, no active compound passes into the water. The quaternary trialkoxysilanes are synthesized in methanol or ethylene glycol monomethyl ether at 110xc2x0 C. in an autoclave.
The solvents which in the above-described prior art are used during the reaction of haloalkyltrialkoxysilanes with tertiary amines or are mixed in after the reaction have the drawbackxe2x80x94which weighs heavily in the textile industry in particularxe2x80x94of having low flash points and being highly flammable. Many of the solvents hitherto used, for example methanol, have a boiling point below the reaction temperatures, so that their use requires that the reaction be carried out under elevated pressure, and this naturally requires increased expenditure on apparatus and safety. Quaternary ammonium compounds having trialkoxysilane substituents are usually solids, depending on the alkyl chain length. Since solids are more costly to handle and meter than liquids, most users prefer liquid formulations.
It is an object of the present invention to develop liquid siloxane quat formulations that do not have the disadvantage of having a low flash point and being highly flammable. The solvents used shall be compatible with the siloxane quats, shall augment the end use and shall have favorable ecotoxicological properties. It is desirable, but not absolutely necessary, for them also to be useful as solvents during the reaction of haloalkyltrialkoxysilanes with tertiary amines. It is a further object to develop a siloxane quat formulation which, even at low concentration, is superior to the prior art with regard to activity against microorganisms such as bacteria and fungi on textile surfaces in particular.
These objects are achieved by the process of the invention for preparing the siloxane quat formulations of the invention using specific glycol ethers or specific dialkylglycols as solvents.
The invention accordingly provides a process for preparing an antimicrobial formulation by reacting a compound of the formula 1
(R1O)3Sixe2x80x94(CH2)3xe2x80x94Xxe2x80x83xe2x80x83(1)
with a compound of the formula 2
(H3C)NR2R3xe2x80x83xe2x80x83(2)
where
R1 is C1-C4-alkyl
R2 is C8-C20-alkyl
R3 is methyl or C8-C20-alkyl
X is Cl or Br,
excluding iodides, in a molar ratio of (1):(2)=1:0.9 to 1:1.4,
which comprises conducting said reaction in a solvent conforming to the formula 3
where
R4 is C1-C4-alkyl
R5 is H or methyl
R6 is H or methyl
m is 2, 3, 4 or 5,
subject to the proviso that when m is 2 R4 and R6 are not both methyl, and not removing this solvent after said reaction, or adding this solvent after said reaction.
The invention further provides an antimicrobial formulation obtainable by the process described above.
In a preferred embodiment of the invention, R1 is methyl. X is preferably chlorine.
In a further preferred embodiment, R2 is C10-C18-alkyl, especially C12-C16-alkyl, specifically a mixture of C12-, C14- and C16-alkyl radicals.
In a further preferred embodiment, R3 is C8-C16-alkyl or methyl. R3 is particularly preferably methyl when R2 is C12-C18-alkyl, especially when R2 is C14-alkyl.
In a further preferred embodiment, R4 is methyl. R5 is preferably hydrogen. R6 is preferably hydrogen. m is preferably 3 or 4.
The process of the invention is preferably carried out at temperatures of 100 to 140xc2x0 C. Temperatures of 110 to 130xc2x0 C. are particularly preferred.
The process is preferably carried out under a dry protective gas in the absence of water. The water content of the solvents should preferably be below 0.1%. Highly suitable solvents are dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, dimethyltetraglycol, dimethylpolyglycbl having an average molar mass of about 200-350 g/mol. Particularly highly suitable are butyldiglycol, methylpolyglycol having an average molar mass of about 200-350 g/mol, and especially methyltriglycol and/or methyltetraglycol. These solvents are compatible with siloxane quats, augment the end use as antimicrobial formulations, possess favorable ecotoxicological properties and do not have the disadvantage of low flash point and high flammability. The reaction of haloalkyltrialkoxysilane with tertiary amine can be carried out in the presence of the abovementioned solvents, but it is preferable to conduct the reaction in the absence of these solvents and to add them only after the reaction has taken place, at a temperature at which the products of the reaction are still liquid. When siloxane quat formulations are prepared in the presence of solvents, small amounts of alcohol may be eliminated from the alkoxy group of the haloalkyltrialkoxysilane. These small amounts of alcohol can, if desired, be removed, for example by distillation or stripping under reduced pressure.
A particularly preferred siloxane quat formulation is prepared by reacting 3-chloropropyltrimethoxysilane and tetradecyldimethylamine in a molar ratio of 1:1 to 1:1.1 at 120xc2x0 C. (xc2x110xc2x0 C.) without solvent and adding methyltriglycol after the reaction has taken place.
The formulation of the invention includes at least one siloxane compound (xe2x80x9csiloxane quatxe2x80x9d), which is preparable by reacting the compounds of the formulae 1 and 2, and a substance as per the formula 3. In a preferred embodiment, the fractions of siloxane quat and of substance of the formula 3 are 20:80 to 80:20% by weight, based on the weight of the formulation. Particular preference is given to fractions of 40:60 to 60:40, especially 45:55 to 55:45, % by weight.
The process of the invention provides compounds of the formula 4
(R1O)3 Sixe2x80x94(CH2)3xe2x80x94+N(CH3)R2R3Xxe2x88x92xe2x80x83xe2x80x83(4)
where R1, R2, R3 and X are each as defined above.
In addition, the process of the invention provides compounds of the formula 5
where k is 1, 2 or 3 and the remaining substituents are each as defined above.
These compounds constitute a further part of the subject-matter of the invention.
The formulations of the invention are useful for conferring an antimicrobial finish on surfaces. These surfaces can be, for example, textile fabrics, glass, wood, cellulose, metals or plastics. When used for finishing textiles, the formulation of the invention is preferably dissolved in water at a concentration of 5 to 100 g/l and applied in that form to the textiles. The amount of formulation remaining on the textiles is generally 0.2 to 3%, preferably 0.5 to 1%, by weight, based on the dry fabric weight.
The formulation of the invention can be applied by padding, exhaustion techniques at bath temperatures of 20 to 70xc2x0 C., foaming or spraying. For spray application, the preferred concentration of the aqueous solution of the formulation according to the invention is 10 to 300 g/l.
The formulation of the invention can be used in the form of an aqueous solution for the antimicrobial finishing of fibers, yarns or fabrics composed of cotton or nylon or polyester or wool or mixtures thereof or of these fiber varieties with polyolefin fibers, preferably polypropylene, by the padding process, by the exhaustion process, by spraying processes or by foaming and application of the foam.
The formulation of the invention can also be used together with other textile chemicals, such as pure or mixed carboxylic acid hand modifiers, such as lactic acid and tartaric acid, such as wax, stearate or silicone sewing thread lubricants, such as silicone or paraffin hydrophobicizers, fluorocarbons with or without melamine derivative extenders, resins such as melamine resins, urea-formaldehyde resins, phenolic resins or polyester resins alone or in combination.
The above-described formulations likewise provide good results on being dissolved in water in concentrations within the range of 5 g/l to 100 g/l and being foamed up with a foaming agent such as an alkanesulfonate, an alkylamine oxide, an alkyl sulfate, an alkyl ether sulfate and salts thereof, preferably an alkyl sulfate, and on applying the foam, which as well as the foaming agent includes the formulation alone or in combination with other textile chemicals, to textiles.
Above-described formulations can be successfully used with good results in combinations with other textile chemicals by using them as solutions, preferably as aqueous solutions, together with other textile chemicals such as hand modifiers, sewing thread lubricants, hydrophobicizers, fluorocarbons with or without extenders, resins to modify the wet crease properties, the anti-slip and anti-laddering finish, permanent hand, stiffening and filling effects and flame retardants, alone or in combination.